Oo! Oo! I got a few:
Blind Faith or Have I Ever Told You the Definition of Insanity?
Liberate all outposts on the southern island before unlocking the radio towers.
Diamonds in the Rough or But I Can't Carry Any More...
Collect all loot chests.
Dead Drop Disgustipated or The Millionth Time's the Charm
Simply land on an enemy from a hang glider, you don't even have to kill them. Good luck!